Sub Effacer_DEF()
Dim w As Worksheet, tablo, ref, i&
For Each w In Worksheets
With w.Range("A1", w.UsedRange).Resize(, 6)
tablo = .Formula 'matrice, plus rapide
ref = .Columns(2).Resize(, 2) 'au moins 2 éléments
For i = 1 To UBound(tablo)
If LCase(CStr(ref(i, 1))) = "pas démarré" Then _
tablo(i, 4) = "": tablo(i, 5) = "": tablo(i, 6) = ""
Next i
.Formula = tablo 'restitution
End With
Next w
End Sub